has_ext('DSN')

mailing.py

@@ -53,7 +53,7 @@ def envoie(serveur,port,login,mdp,sujet,corps,emet,dest,dobcc,file_path,filename
     with SMTP_SSL(serveur,port) as server:
         server.login(login,mdp)
         try:
-            if conf['mail']['dsn']=='true':
+            if conf['mail']['dsn']=='true' and server.has_extn('DSN'):
                 server.send_message(msg,rcpt_options=['NOTIFY=SUCCESS,DELAY,FAILURE'])
             else:
                 server.send_message(msg)